The natural teeth of an individual may be lost as a result of dental disease or trauma, making it desirable to replace such teeth with one or more prosthetic devices. An example of a prosthetic device is the dental implant which is surgically positioned within the mandibular or maxillary alveolar bone.
One type of dental implant has a first implant member for placement in an osteotomy site in the alveolar bone of a patient. Following healing, a head member, commonly called an abutment, is mounted in or on the first implant member and a tooth simulating prosthesis or crown is then mounted on the abutment. A successful system of this type is disclosed in U.S. Pat. No. 4,738,623. In that patent, a first implant or root member having a first or outer end formed with a female socket circumscribed by a shoulder and having a suitable anchoring means, such as outwardly extending fins, is placed in an osteotomy site or implant receiving cavity formed in the alveolar bone with suitable surgical instruments and techniques. The first implant member is inserted into the cavity with the upper portion of the member a selected distance below the opening of the cavity, that is, below the crest of the bone, e.g., two or three millimeters. A healing plug is inserted into a female socket of the first implant member and particles of a natural and/or synthetic bone growth stimulating grafting material are then packed within the cavity around the shoulder of the implant member and the wound is then closed.
Following healing, the dentist accesses and removes the plug and replaces it with an abutment. The abutment has a male portion received within the female socket and an intermediate, outer generally hemispherical surface portion which may extend through the surface of the gingiva and preferably through the surface of the crest of the bone which may have been previously reamed to form a complimentary configuration when forming the cavity. A prosthetic device can then be attached to the abutment forming a smooth continuous surface with the hemispherical surface portion of the abutment with the interface between the prosthetic device and the abutment being supragingival or, for best aesthetics, subgingival, that is, being covered by the gingival tissue. Fabrication of the prosthetic device typically involves making an impression, generally a full arch impression, and pouring a model forming, inter alia, a positive replica, or die, of the abutment head. A laboratory technician then burnishes platinum foil over the die which then serves as a core on which a prosthesis is built. Upon completion and firing of the prosthesis, the platinum is scratched away. Although this procedure has been acceptable, the efficacy of the result is dependent upon the skill of the technician and is highly labor intensive and time consuming. Alternatively, the technician could fabricate the prosthesis by a lost wax technique utilizing a central core of metal, usually a gold palladium alloy, onto which porcelain powders are added and fused in a firing oven. Still other techniques for prosthesis fabrication include the use of implant and abutment analogs, acrylics or composite resins. However, such methods are also highly labor intensive and time consuming.